WASHINGTON (CNN) -- The top U.S. commander in Iraq will recommend to President Bush that current U.S. troop levels be maintained in Iraq through next spring, according to U.S. military officials.

Gen. David Petraeus talks with President Bush during Bush's visit to Iraq earlier this week.

Under dispute are published reports that Gen. David Petraeus would consider pulling out a brigade of between 3,500 and 4,000 U.S. troops early next year to "assuage critics in Congress."

"That's total nonsense," one military official told CNN, speaking on condition of anonymity because Petraeus' recommendations have not been made public.

The official said that while Bush will make any decision on troop reductions, if he pulls a brigade out, "it won't be on the recommendation of Gen. Petraeus. He believes every brigade is important."

Under the current plan, the number of U.S. troops would drop from more than 160,000 to around 130,000 beginning in March or April 2008 because of already scheduled rotations. About 168,000 troops are in Iraq because of overlaps while some units swap out.

Petraeus and U.S. Ambassador to Iraq Ryan Crocker are to report to Congress next week on progress in the war. Petraeus is expected to testify next week that the surge has produced progress on the ground.

Bush will then present a report to Congress on Iraq war strategy based in part on Petraeus' and Crocker's recommendations.

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A senior administration official told CNN on Friday that it is "very likely" Bush will speak to the nation about Iraq in a prime-time address from the White House next week.

The official said the speech would be aimed at both reporting directly to the American people about Petraeus' and Crocker's findings, as well as trying to re-frame the debate as Congress prepares to vote on timetables to withdraw U.S. troops from Iraq.

In a letter to Multi-National Force-Iraq troops dated Friday, Petraeus told American troops that "tactical momentum" has been achieved in the war and that the "initiative" has been "wrested from our enemies in a number of areas."

At the same time, Petraeus said that "tangible political progress" has not unfolded as hoped for during the "surge" and that overall military progress has been "uneven."

"We are, in short, a long way from the goal line, but we do have the ball and we are driving down the field," he said. Petraeus noted the combat challenges, the political and military complexities, and the pressing sectarian strife in the country.

Days before Petraeus is scheduled to testify on the progress of the troop surge, the Senate's No. 2 Democrat is accusing the administration of manipulating information in its highly anticipated Iraq report.

"By carefully manipulating the statistics, the Bush-Petraeus report will try to persuade us that violence in Iraq is decreasing and thus the surge is working," Sen. Dick Durbin of Illinois told a Washington think tank.

Durbin, a war critic, said for a long period of time, he has e-mailed civilian employees who were gathering data for the report and writing draft portions of the findings.

"Some of them I correspond with almost on a daily basis. And when they sent a discouraging report about things that were happening in Baghdad, they were reminded by their superiors that's unacceptable, we need a positive report. They were sent back for editing changes. Now that's a fact," Durbin said.

A senior administration official called Durbin's charges "absurd" and pledged that the report will have "accurate data."

In recent days, congressional Democrats have tried to minimize the impact of testimony that could undermine their ability to convince wavering Republicans to vote for troop withdrawals.

"He's made a number of statements over the years that have not proved to be factual," Reid said. "I have every belief that this good man, Gen. Petraeus, will give us what he feels is the right thing to do in the report that is now not his report. It's President Bush's report."

A Senate Republican leadership aide responded to the Democrats' broadsides. "My guess is that it's an attempt to discredit the witness," the aide said.

"The problem is Petraeus' approval rating is about four times higher than the Democrat Congress."

The statistics that Durbin is questioning deal with the accounting of sectarian violence -- which Petraeus is expected to report has gone down in recent months.

But in testimony before the Senate Armed Services Committee on Friday, David Walker, the head of the nonpartisan Government Accountability Office, also questioned how those statistics were compiled.

He said he is "not comfortable" with the methodology used to count the death toll from sectarian violence. Specifically, if a body is found with a gunshot in the front of the head, the death is classified as an ordinary crime. But if the bullet is in the back of the head, the death is considered sectarian violence, according to the GAO.

Walker said he would "fully expect" such a methodology to reflect a reduction in sectarian violence.

He said those statistics are kept by the Multi-National Force-Iraq, which Petraeus commands. Walker said the methodology details are classified and urged senators to push for the information to be declassified.E-mail to a friend